Pygmy resonances and neutron skins
Pygmy resonances and neutron skins
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DOI：
10.1103/physrevc.83.034319
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发表时间：
2010-12
影响因子：
3.1
通讯作者：
J. Piekarewicz
中科院分区：
文献类型：
--
作者：
J. Piekarewicz
在一项由最近的实验激发的研究中，利用一组有效相互作用的相对论随机相近似计算了富中子{sup 68}Ni同位素中电偶极子强度的分布，尽管校准得很好，但预测了{sup 208}Pb中中子皮厚度的显着不同值。低能量“侏儒”强度的出现，耗尽了大约5%-8%的能量加权和规则（EWSR）。除了EWSR外，还特别强调了偶极子极化率。特别是，我们的结果表明{sup 68}Ni的偶极极化率与{sup 208}Pb的中子皮厚度之间存在很强的相关性。然而，我们发现，在Pb的中子皮厚度和由侏儒共振耗尽的偶极极化率之间，存在着同样强烈的相关性，而且灵敏度更高。这些发现表明偶极极化率可以作为中子表皮的一个替代指标。
In a study motivated by a recent experiment, the distribution of electric dipole strength in the neutron-rich {sup 68}Ni isotope was computed using a relativistic random-phase approximation with a set of effective interactions that - although well calibrated - predict significantly different values for the neutron-skin thickness in {sup 208}Pb. The emergence of low-energy 'pygmy' strength that exhausts about 5%-8% of the energy-weighted sum rule (EWSR) is clearly identified. In addition to the EWSR, special emphasis is placed on the dipole polarizability. In particular, our results suggest a strong correlation between the dipole polarizability of {sup 68}Ni and the neutron-skin thickness of {sup 208}Pb. Yet we find a correlation just as strong, and an even larger sensitivity, between the neutron-skin thickness of {sup 208}Pb and the fraction of the dipole polarizability exhausted by the pygmy resonance. These findings suggest that dipole polarizability may be used as a proxy for the neutron skin.